Characterizations of H4 avian influenza viruses isolated from ducks in live poultry markets and farm in Shanghai

Abstract

H4 avian influenza virus is one of the most prevalent influenza virus subtypes in birds. The evolution and pathogenicity of H4 AIV in domestic birds of China remain largely unclear. In the present study, a total of eight H4 AIV strains isolated in duck farm and live poultry markets (LPM) were characterized. Phylogenetic analysis indicated that these strains are divided into two groups in the Eurasian lineage. Eight genes of MH-2/H4N6 isolated from a duck farm were closely related to three H4N6 viruses from LPM, suggesting a potential AIV link between farms and LPMs. Additionally, the HA, NA, PB2, NP, and NS genes of two other H4N6 viruses isolated in LPM clustered with that of MH-2/H4N6. However, the remaining genes were more closely related to other sublineages, suggesting that MH-2/H4N6-originated viruses reassorted with other viruses in LPM. All H4 viruses replicated in mouse lungs without prior adaptation and all viruses replicated and transmitted among ducks. 29-1/H4N2, MH-2/H4N6, and 420-2/H4N6 viruses caused systemic infection in infected ducks. However, most of the viruses were not adapted in chickens. The present results indicate a potential correlation of AIV between LPMs and farms and suggest that active surveillance of AIV in LPM is warranted in China.

Avian-to-Human Receptor-Binding Adaptation by Influenza A Virus Hemagglutinin H4

“…Since the first H4 strain was isolated from a duck in the former Czechoslovakia in 1956, the H4 LPAIV has been discovered to be widely circulating in wild and domestic avian species in Asian, European, and North American countries (Bui et al, 2012;Donis et al, 1989;Kang et al, 2013;Liang et al, 2015;Teng et al, 2012;Wu et al, 2015;Yuan et al, 2015). In recent years, multiple genotypes of H4 viruses have been shown to be co-circulating in the live poultry markets of Central, Eastern, and Southern China, and complex reassortment events between H4 subtype viruses and other subtype viruses (e.g., H3 subtype virus) have actively occurred in domestic ducks (Deng et al, 2013;Liang et al, 2015;Shi et al, 2016;Wu et al, 2015;Yuan et al, 2015). H4 subtype viruses can replicate in mice without prior adaptation and transmit between guinea pigs via direct contact (Kang et al, 2013;Liang et al, 2015).…”

H9N2 influenza virus isolated from minks has enhanced virulence in mice

“…To further characterize the two viruses, eight fragments of each virus were amplified and sequenced as described previously (Shi et al., ). The sequences were deposited to GenBank with accession number of –.…”

Isolation and characterization of H4N6 avian influenza viruses from mallard ducks in Beijing, China

“…Additionally, mutations related to the enhanced virulence and transmission of influenza viruses in mammals, including PB2-627K and -701N, were also not observed in any of the four isolated viruses. H4N6 strains previously isolated from domestic ducks in China also did not possess these mutations related to mammalian adaptation [ 13 , 14 , 28 ]. Hossain et al demonstrated that duck influenza virus could acquire mammalian-associated genetic changes after adaptation in land-based birds, including chickens and quail [ 29 ].…”

“…It has been noted that H4N6 viruses have been repeatedly found in mammalian species, such as humans and pigs [ 7 – 11 ]. H4N6 is frequently isolated from domestic ducks in China [ 12 – 14 ]. Genetic analysis indicates that these H4N6 viruses are undergoing complex and frequent reassortment events.…”